Random musings on hifi components from 20+ years of upgraditis

Derek S-H

No mention of headphone amps versus the standard jack on an integrated?

I suppose if your integrated can drive your headphones okay then there's no issue, but the blurb that comes with headphone amps is very persuasive. Professional reviews are similar too.

gibbsy

If you look at the size of my headphone amp it would certainly take up a fair bit of room where it to be integrated into a stereo amp. Headphone circuits have to be fitted within existing amps competing for room and for costings, on that basis you would think that a standalone headphone amp would have the edge. Horses for courses so to say.

Would have bought a Lehmann had the Rega had it's own circuit and headphone jack. I don't think I can answer that without actually trying a standalone against the integrated stereo amp back to back. The other problem comes with most manufacturers not publishing the actual power of the headphone section of their amps.

Derek S-H

Would you say that the headphone jack on an integrated is underpowered, then?

I know it's all supposition and hypothesis and I guess you also know why I'm bringing this up as a topic! Your Lehmann is huge! But some headphone amps are tiny but still claim to have large power outputs, like the JDS Atom.

Derek S-H

Okay, I've just looked up the specifications of my Arcam FMJ A32 integrated and it says:

Headphone Output

Maximum output level into 600 ohms - 8V (volts?)
Output impedance - 100 ohms

Enough to drive a pair of Sennheiser HD 800S, @gibbsy?

Sorry this is OT, won't ask again!

TheHighFlyingBirds

I was too late to the party, so have a raspberry pi with a touchscreen and dac in my setup being fed like yours (synology NAS with LMS). Brilliant streamer with nice big display for album artwork or vu meters.

gibbsy

Here's the Linear's figures. How it equates to the voltage signal of the Arcam I can't really work out. As a comparison the rHead has 130mW into the 300 ohms needed to drive the Senns. So the Lehmann is more powerful. Perhaps someone with more brains than me can work out the difference in figures between the FMJ and the Lehmann.

  
Output power400 mW/60 ohms
200 mW/300 ohmsOutput impedancepre-out 50 ohms
phones out 5 ohm

dannnielll

Hi Gibbsy. Auditioning for the brains trust.  The figure for the Linear is that when driving 300 ohm loads, it will provide 7.7 volts  at peak output power, but if the load is as low as 60 ohms  ,it can due to its own internal resistance,, only generate a peak voltage of 4.9 V.
The rHead driving the senns at 300 ohms can manage  6.2 v
The FMJ..and using the figures quoted above  will produce About 6.0 V .
...300/(100  300)   * 8

gibbsy

Still lost, well maybe still wandering and thanks for replying. It seems that the lower the ohm rating on the headphones themselves then that has an effect on voltage. My Oppos PM1s are just 32ohm and was bought initially because I really wanted to try planars but was instantly smitten by their performance. The other reason was that I could easily use them with the low powered headphone sockets that are fitted to my Marantz players. Which is something they did quite well. Now that they have the power of Lehmann they really do sing.

Does voltage then, influence the performance of the headphones? I did audition the Senn 800s but they were being driven by an amp (Project Head), found them a wee bit bright for my tastes, especially on female vocals, plus the 300 ohm loading for the reasons above. Then I went and bought the Oppos completely blind.

Derek S-H

Christ, the Sennheisers are here!

Okay, simple question @dannnielll - is my Arcam amp's headphone output powerful enough or do I really need a separate headphone amp?

Thanks!

dannnielll

The Arcam quotes a 50 ohm output impedance, and it is driving phones of 300 ohms. This means that the Arcam is strongly controlling the phones. ..If the amplifier says jump, the phones jump ,if the amplifier says stop, the 'phones stop quickly .  Whether you like this or not is a matter for yourself. One of the "attractions " of many valve amplifiers is that they do not control the headphone or speaker so if the amplifier says stop the speaker slows  down at its own sluggish rate.
There is very little difference between 6 ,6.2 and 7.0 volts, and I expect that anything at that level will be blowing your ears off , and you will normally be listening at a level of 1.0 V. so No, in terms of power.
But it would be possible to get headphone amplifiers with 5 ohm or 1 ohm output impedances, and they would even exert greater control.
I am operating in a different league, but the same argument follows.  I have reasonably good headphones in the Sony MDR1A,and have used them in a variety of situations over the last 5 years... With music players, PCs DACs ,Music Centres .They have a high efficiency and have 50 ohm impedance. They sound completely different when driven from a standard mobile phone than when driven with exactly the same music source but instead  from  a Cyrus Soundkey DAC Headphone amplifier. In all cases the sound is clear ,but in the case of the Soundkey it is dynamic, fuller stronger .. substitute your own positive adjective. It is not a volume thing as in all cases the volume can be brought up to excessive.  No it is because the output impedance of the Soundkey is 1.1ohms,  which means it controls the phones.  
Now the Soundkey tops out at 1.7 volts peak, which is very low compared to your peaks of 7.0 volts!.